Organic light emitting diode (OLED) panel has a faster response, lighter weight, lesser viewing angle restrictions and greater contrast compared with a liquid crystal display panel, and thus has drawn great attention of the display industry. The OLED panel can be classified as a passive matrix organic light emitting diode (PMOLED) panel or an active matrix organic light emitting diode (AMOLED) panel. Generally, the AMOLED panel is particularly adapted to the production of high resolution and large size display panels.
The brightness of a pixel in the AMOLED panel is proportional to the conducting current of the organic light emitting diode and the conducting current is decided by thin film transistors (TFTs). In other words, the emission property, such as brightness and uniformity of emitted light, of the AMOLED is very sensitive to the performance of the TFTs.
Particularly, for an AMOLED display panel having a low-temperature polysilicon (LTPS) backplane crystallized by the excimer laser anneling (ELA), crystallization and non-uniformity of defeats may result in a line mura effect in the display panel, as shown in FIG. 1. The mura defects are defects that exhibit as non-uniform contract regions on OLED display pane and are attributed to pulse-to-pulse variations in the laser beam energy that is used to crystallize the amorphous silicon film. These defects are more pronounced when a constant gray value image or pattern is displayed. In AMOLED display panels, the laser annal irradiation of the non-TFT regions, such as the OLED circuit portion, on the TFT back panel often results in line-shaped mura defects. The non-uniform laser beam energy caused by pulse-to-pulse variations in the laser beam energy results in a non-uniform performance of polycrystalline silicon. Since the TFT characteristic is sensitive to the performance of the polycrystalline silicon, and the TFT devices drive the OLED devices, the non-uniform TFT characteristics result in non-uniformity in OLED's brightness. This non-uniformity causes the line mura defects, which deteriorate the display quality of the AMOLED display panel.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.